Johnny E., it sounds like your problem is different that what everyone else has chimed in with. It also sounds like you've addressed the issue. I was going to recommend lubricating and checking your throttle cable and linkage. Also cleaning the throttle body could help out. My throttle was sticking shut, so I removed it, cleaned it, and went the extra mile to adjust the set screw to keep the plate out a little further. I was thinking that your butterfly was sticking inside the throttle body, or the linkage on the outside of the throttle body was causing a problem.
As far as the throttle pedal buzzing, I get the same thing too. It happens only under cruise control, and only when the cruise dials in more throttle when encountering an incline. So, the buzzing is caused by a resonance as created by the greater engine load. On flat terrain, there is no buzzing.
I have also noticed that when I lay my foot on the pedal (barely touching it) the buzzing goes away. This leads me to believe that the noise is coming from the pivot between the throttle pedal and the pedal arm. I don't think it's between the pedal arm and the throttle cable.
I haven't done anything about it yet, but I'm going to start with some lithium grease on the throttle pedal pivot.
2003 Ford Ranger | FX4 Level II | 5-Speed Manual
A few minor mods... nothing cool enough to mention.